The invention concerns filter construction and a method for the formation of a filter construction.
In prior-art ceramic filter plates, which were already patented by Valmet earlier, the filter construction favourably comprises a first suction face and a second suction face, between which there is a space filled by granules. The said intermediate space acts as a water space or liquid space, into which the liquid sucked out of the material to be filtered is sucked first. The granules or equivalent are substantially confined by the first face and by the second face, and they act as rigidifiers of the construction. The granularity does, however, not prevent the flow of the liquid that has entered into the space, because the granules do not cause a high resistance to flow. Into the central space, a connecting duct is passed, which can further be connected to a source of negative pressure so as to produce flow of liquid through the suction faces into the central space and further out of the filter plate. In the filter construction, the suction faces of the plate are preferably made of a ceramic casting mix.
Filter constructions are known in which the filtering face of the filter consists of a synthetic membrane. However, a major drawback in the case of membrane filters is the risk of damage to the film on cleaning.